/* pngpread.c - read a png file in push mode
 *
 * Last changed in libpng 1.4.1 [February 25, 2010]
 * Copyright (c) 1998-2010 Glenn Randers-Pehrson
 * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
 * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
 *
 * This code is released under the libpng license.
 * For conditions of distribution and use, see the disclaimer
 * and license in png.h
 */

#include "png.h"
#define PNG_NO_PEDANTIC_WARNINGS
#ifdef PNG_PROGRESSIVE_READ_SUPPORTED
    #include "pngpriv.h"

/* Push model modes */
    #define PNG_READ_SIG_MODE 0
    #define PNG_READ_CHUNK_MODE 1
    #define PNG_READ_IDAT_MODE 2
    #define PNG_SKIP_MODE 3
    #define PNG_READ_tEXt_MODE 4
    #define PNG_READ_zTXt_MODE 5
    #define PNG_READ_DONE_MODE 6
    #define PNG_READ_iTXt_MODE 7
    #define PNG_ERROR_MODE 8

void PNGAPI
png_process_data(png_structp png_ptr, png_infop info_ptr,
                 png_bytep buffer, png_size_t buffer_size)
{
    if (png_ptr == NULL || info_ptr == NULL)
        return;

    png_push_restore_buffer(png_ptr, buffer, buffer_size);

    while (png_ptr->buffer_size)
    {
        png_process_some_data(png_ptr, info_ptr);
    }
}

/* What we do with the incoming data depends on what we were previously
 * doing before we ran out of data...
 */
void /* PRIVATE */
png_process_some_data(png_structp png_ptr, png_infop info_ptr)
{
    if (png_ptr == NULL)
        return;

    switch (png_ptr->process_mode)
    {
        case PNG_READ_SIG_MODE:
        {
            png_push_read_sig(png_ptr, info_ptr);
            break;
        }

        case PNG_READ_CHUNK_MODE:
        {
            png_push_read_chunk(png_ptr, info_ptr);
            break;
        }

        case PNG_READ_IDAT_MODE:
        {
            png_push_read_IDAT(png_ptr);
            break;
        }

            #ifdef PNG_READ_tEXt_SUPPORTED
        case PNG_READ_tEXt_MODE:
        {
            png_push_read_tEXt(png_ptr, info_ptr);
            break;
        }

            #endif
            #ifdef PNG_READ_zTXt_SUPPORTED
        case PNG_READ_zTXt_MODE:
        {
            png_push_read_zTXt(png_ptr, info_ptr);
            break;
        }

            #endif
            #ifdef PNG_READ_iTXt_SUPPORTED
        case PNG_READ_iTXt_MODE:
        {
            png_push_read_iTXt(png_ptr, info_ptr);
            break;
        }

            #endif
        case PNG_SKIP_MODE:
        {
            png_push_crc_finish(png_ptr);
            break;
        }

        default:
        {
            png_ptr->buffer_size = 0;
            break;
        }
    }
}

/* Read any remaining signature bytes from the stream and compare them with
 * the correct PNG signature.  It is possible that this routine is called
 * with bytes already read from the signature, either because they have been
 * checked by the calling application, or because of multiple calls to this
 * routine.
 */
void /* PRIVATE */
png_push_read_sig(png_structp png_ptr, png_infop info_ptr)
{
    png_size_t num_checked = png_ptr->sig_bytes,
               num_to_check = 8 - num_checked;

    if (png_ptr->buffer_size < num_to_check)
    {
        num_to_check = png_ptr->buffer_size;
    }

    png_push_fill_buffer(png_ptr, &(info_ptr->signature[num_checked]),
                         num_to_check);
    png_ptr->sig_bytes = (png_byte)(png_ptr->sig_bytes + num_to_check);

    if (png_sig_cmp(info_ptr->signature, num_checked, num_to_check))
    {
        if (num_checked < 4 &&
            png_sig_cmp(info_ptr->signature, num_checked, num_to_check - 4))
            png_error(png_ptr, "Not a PNG file");
        else
            png_error(png_ptr, "PNG file corrupted by ASCII conversion");
    }
    else
    {
        if (png_ptr->sig_bytes >= 8)
        {
            png_ptr->process_mode = PNG_READ_CHUNK_MODE;
        }
    }
}

void /* PRIVATE */
png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
{
    PNG_IHDR;
    PNG_IDAT;
    PNG_IEND;
    PNG_PLTE;
    #ifdef PNG_READ_bKGD_SUPPORTED
    PNG_bKGD;
    #endif
    #ifdef PNG_READ_cHRM_SUPPORTED
    PNG_cHRM;
    #endif
    #ifdef PNG_READ_gAMA_SUPPORTED
    PNG_gAMA;
    #endif
    #ifdef PNG_READ_hIST_SUPPORTED
    PNG_hIST;
    #endif
    #ifdef PNG_READ_iCCP_SUPPORTED
    PNG_iCCP;
    #endif
    #ifdef PNG_READ_iTXt_SUPPORTED
    PNG_iTXt;
    #endif
    #ifdef PNG_READ_oFFs_SUPPORTED
    PNG_oFFs;
    #endif
    #ifdef PNG_READ_pCAL_SUPPORTED
    PNG_pCAL;
    #endif
    #ifdef PNG_READ_pHYs_SUPPORTED
    PNG_pHYs;
    #endif
    #ifdef PNG_READ_sBIT_SUPPORTED
    PNG_sBIT;
    #endif
    #ifdef PNG_READ_sCAL_SUPPORTED
    PNG_sCAL;
    #endif
    #ifdef PNG_READ_sRGB_SUPPORTED
    PNG_sRGB;
    #endif
    #ifdef PNG_READ_sPLT_SUPPORTED
    PNG_sPLT;
    #endif
    #ifdef PNG_READ_tEXt_SUPPORTED
    PNG_tEXt;
    #endif
    #ifdef PNG_READ_tIME_SUPPORTED
    PNG_tIME;
    #endif
    #ifdef PNG_READ_tRNS_SUPPORTED
    PNG_tRNS;
    #endif
    #ifdef PNG_READ_zTXt_SUPPORTED
    PNG_zTXt;
    #endif

    /* First we make sure we have enough data for the 4 byte chunk name
     * and the 4 byte chunk length before proceeding with decoding the
     * chunk data.  To fully decode each of these chunks, we also make
     * sure we have enough data in the buffer for the 4 byte CRC at the
     * end of every chunk (except IDAT, which is handled separately).
     */
    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
    {
        png_byte chunk_length[4];

        if (png_ptr->buffer_size < 8)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_push_fill_buffer(png_ptr, chunk_length, 4);
        png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
        png_reset_crc(png_ptr);
        png_crc_read(png_ptr, png_ptr->chunk_name, 4);
        png_check_chunk_name(png_ptr, png_ptr->chunk_name);
        png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;
    }

    if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
        if (png_ptr->mode & PNG_AFTER_IDAT)
            png_ptr->mode |= PNG_HAVE_CHUNK_AFTER_IDAT;

    if (!png_memcmp(png_ptr->chunk_name, png_IHDR, 4))
    {
        if (png_ptr->push_length != 13)
            png_error(png_ptr, "Invalid IHDR length");

        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_IHDR(png_ptr, info_ptr, png_ptr->push_length);
    }

    else if (!png_memcmp(png_ptr->chunk_name, png_IEND, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_IEND(png_ptr, info_ptr, png_ptr->push_length);

        png_ptr->process_mode = PNG_READ_DONE_MODE;
        png_push_have_end(png_ptr, info_ptr);
    }

    #ifdef PNG_HANDLE_AS_UNKNOWN_SUPPORTED
    else if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
            png_ptr->mode |= PNG_HAVE_IDAT;

        png_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);

        if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
            png_ptr->mode |= PNG_HAVE_PLTE;

        else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
        {
            if (!(png_ptr->mode & PNG_HAVE_IHDR))
                png_error(png_ptr, "Missing IHDR before IDAT");

            else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
                     !(png_ptr->mode & PNG_HAVE_PLTE))
                png_error(png_ptr, "Missing PLTE before IDAT");
        }
    }

    #endif
    else if (!png_memcmp(png_ptr->chunk_name, png_PLTE, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }
        png_handle_PLTE(png_ptr, info_ptr, png_ptr->push_length);
    }

    else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
    {
        /* If we reach an IDAT chunk, this means we have read all of the
         * header chunks, and we can start reading the image (or if this
         * is called after the image has been read - we have an error).
         */

        if (!(png_ptr->mode & PNG_HAVE_IHDR))
            png_error(png_ptr, "Missing IHDR before IDAT");

        else if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE &&
                 !(png_ptr->mode & PNG_HAVE_PLTE))
            png_error(png_ptr, "Missing PLTE before IDAT");

        if (png_ptr->mode & PNG_HAVE_IDAT)
        {
            if (!(png_ptr->mode & PNG_HAVE_CHUNK_AFTER_IDAT))
                if (png_ptr->push_length == 0)
                    return;

            if (png_ptr->mode & PNG_AFTER_IDAT)
                png_benign_error(png_ptr, "Too many IDATs found");
        }

        png_ptr->idat_size = png_ptr->push_length;
        png_ptr->mode |= PNG_HAVE_IDAT;
        png_ptr->process_mode = PNG_READ_IDAT_MODE;
        png_push_have_info(png_ptr, info_ptr);
        png_ptr->zstream.avail_out =
            (uInt)PNG_ROWBYTES(png_ptr->pixel_depth,
                               png_ptr->iwidth) + 1;
        png_ptr->zstream.next_out = png_ptr->row_buf;
        return;
    }

    #ifdef PNG_READ_gAMA_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_gAMA, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_gAMA(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_sBIT_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_sBIT(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_cHRM_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_cHRM, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_sRGB_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_iCCP_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_iCCP, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_iCCP(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_sPLT_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_sPLT, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_sPLT(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_tRNS_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_tRNS(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_bKGD_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_bKGD, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_bKGD(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_hIST_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_hIST, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_hIST(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_pHYs_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_pHYs, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_pHYs(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_oFFs_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_oFFs, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_oFFs(png_ptr, info_ptr, png_ptr->push_length);
    }
    #endif

    #ifdef PNG_READ_pCAL_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_pCAL, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_pCAL(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_sCAL_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_sCAL, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_sCAL(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_tIME_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_tIME, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_handle_tIME(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_tEXt_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_push_handle_tEXt(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_zTXt_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_zTXt, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_push_handle_zTXt(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    #ifdef PNG_READ_iTXt_SUPPORTED
    else if (!png_memcmp(png_ptr->chunk_name, png_iTXt, 4))
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_push_handle_iTXt(png_ptr, info_ptr, png_ptr->push_length);
    }

    #endif
    else
    {
        if (png_ptr->push_length + 4 > png_ptr->buffer_size)
        {
            png_push_save_buffer(png_ptr);
            return;
        }
        png_push_handle_unknown(png_ptr, info_ptr, png_ptr->push_length);
    }

    png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
}

void /* PRIVATE */
png_push_crc_skip(png_structp png_ptr, png_uint_32 skip)
{
    png_ptr->process_mode = PNG_SKIP_MODE;
    png_ptr->skip_length = skip;
}

void /* PRIVATE */
png_push_crc_finish(png_structp png_ptr)
{
    if (png_ptr->skip_length && png_ptr->save_buffer_size)
    {
        png_size_t save_size;

        if (png_ptr->skip_length < (png_uint_32)png_ptr->save_buffer_size)
            save_size = (png_size_t)png_ptr->skip_length;
        else
            save_size = png_ptr->save_buffer_size;

        png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);

        png_ptr->skip_length -= save_size;
        png_ptr->buffer_size -= save_size;
        png_ptr->save_buffer_size -= save_size;
        png_ptr->save_buffer_ptr += save_size;
    }
    if (png_ptr->skip_length && png_ptr->current_buffer_size)
    {
        png_size_t save_size;

        if (png_ptr->skip_length < (png_uint_32)png_ptr->current_buffer_size)
            save_size = (png_size_t)png_ptr->skip_length;
        else
            save_size = png_ptr->current_buffer_size;

        png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);

        png_ptr->skip_length -= save_size;
        png_ptr->buffer_size -= save_size;
        png_ptr->current_buffer_size -= save_size;
        png_ptr->current_buffer_ptr += save_size;
    }
    if (!png_ptr->skip_length)
    {
        if (png_ptr->buffer_size < 4)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_crc_finish(png_ptr, 0);
        png_ptr->process_mode = PNG_READ_CHUNK_MODE;
    }
}

void PNGAPI
png_push_fill_buffer(png_structp png_ptr, png_bytep buffer, png_size_t length)
{
    png_bytep ptr;

    if (png_ptr == NULL)
        return;

    ptr = buffer;
    if (png_ptr->save_buffer_size)
    {
        png_size_t save_size;

        if (length < png_ptr->save_buffer_size)
            save_size = length;
        else
            save_size = png_ptr->save_buffer_size;

        png_memcpy(ptr, png_ptr->save_buffer_ptr, save_size);
        length -= save_size;
        ptr += save_size;
        png_ptr->buffer_size -= save_size;
        png_ptr->save_buffer_size -= save_size;
        png_ptr->save_buffer_ptr += save_size;
    }
    if (length && png_ptr->current_buffer_size)
    {
        png_size_t save_size;

        if (length < png_ptr->current_buffer_size)
            save_size = length;

        else
            save_size = png_ptr->current_buffer_size;

        png_memcpy(ptr, png_ptr->current_buffer_ptr, save_size);
        png_ptr->buffer_size -= save_size;
        png_ptr->current_buffer_size -= save_size;
        png_ptr->current_buffer_ptr += save_size;
    }
}

void /* PRIVATE */
png_push_save_buffer(png_structp png_ptr)
{
    if (png_ptr->save_buffer_size)
    {
        if (png_ptr->save_buffer_ptr != png_ptr->save_buffer)
        {
            png_size_t i, istop;
            png_bytep sp;
            png_bytep dp;

            istop = png_ptr->save_buffer_size;
            for (i = 0, sp = png_ptr->save_buffer_ptr, dp = png_ptr->save_buffer;
                 i < istop; i++, sp++, dp++)
            {
                *dp = *sp;
            }
        }
    }
    if (png_ptr->save_buffer_size + png_ptr->current_buffer_size >
        png_ptr->save_buffer_max)
    {
        png_size_t new_max;
        png_bytep old_buffer;

        if (png_ptr->save_buffer_size > PNG_SIZE_MAX -
            (png_ptr->current_buffer_size + 256))
        {
            png_error(png_ptr, "Potential overflow of save_buffer");
        }

        new_max = png_ptr->save_buffer_size + png_ptr->current_buffer_size + 256;
        old_buffer = png_ptr->save_buffer;
        png_ptr->save_buffer = (png_bytep)png_malloc_warn(png_ptr,
                                                          (png_size_t)new_max);
        if (png_ptr->save_buffer == NULL)
        {
            png_free(png_ptr, old_buffer);
            png_error(png_ptr, "Insufficient memory for save_buffer");
        }
        png_memcpy(png_ptr->save_buffer, old_buffer, png_ptr->save_buffer_size);
        png_free(png_ptr, old_buffer);
        png_ptr->save_buffer_max = new_max;
    }
    if (png_ptr->current_buffer_size)
    {
        png_memcpy(png_ptr->save_buffer + png_ptr->save_buffer_size,
                   png_ptr->current_buffer_ptr, png_ptr->current_buffer_size);
        png_ptr->save_buffer_size += png_ptr->current_buffer_size;
        png_ptr->current_buffer_size = 0;
    }
    png_ptr->save_buffer_ptr = png_ptr->save_buffer;
    png_ptr->buffer_size = 0;
}

void /* PRIVATE */
png_push_restore_buffer(png_structp png_ptr, png_bytep buffer,
                        png_size_t buffer_length)
{
    png_ptr->current_buffer = buffer;
    png_ptr->current_buffer_size = buffer_length;
    png_ptr->buffer_size = buffer_length + png_ptr->save_buffer_size;
    png_ptr->current_buffer_ptr = png_ptr->current_buffer;
}

void /* PRIVATE */
png_push_read_IDAT(png_structp png_ptr)
{
    PNG_IDAT;
    if (!(png_ptr->mode & PNG_HAVE_CHUNK_HEADER))
    {
        png_byte chunk_length[4];

        if (png_ptr->buffer_size < 8)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_push_fill_buffer(png_ptr, chunk_length, 4);
        png_ptr->push_length = png_get_uint_31(png_ptr, chunk_length);
        png_reset_crc(png_ptr);
        png_crc_read(png_ptr, png_ptr->chunk_name, 4);
        png_ptr->mode |= PNG_HAVE_CHUNK_HEADER;

        if (png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
        {
            png_ptr->process_mode = PNG_READ_CHUNK_MODE;
            if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
                png_error(png_ptr, "Not enough compressed data");
            return;
        }

        png_ptr->idat_size = png_ptr->push_length;
    }
    if (png_ptr->idat_size && png_ptr->save_buffer_size)
    {
        png_size_t save_size;

        if (png_ptr->idat_size < (png_uint_32)png_ptr->save_buffer_size)
        {
            save_size = (png_size_t)png_ptr->idat_size;

            /* Check for overflow */
            if ((png_uint_32)save_size != png_ptr->idat_size)
                png_error(png_ptr, "save_size overflowed in pngpread");
        }
        else
            save_size = png_ptr->save_buffer_size;

        png_calculate_crc(png_ptr, png_ptr->save_buffer_ptr, save_size);

        if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
            png_process_IDAT_data(png_ptr, png_ptr->save_buffer_ptr, save_size);

        png_ptr->idat_size -= save_size;
        png_ptr->buffer_size -= save_size;
        png_ptr->save_buffer_size -= save_size;
        png_ptr->save_buffer_ptr += save_size;
    }
    if (png_ptr->idat_size && png_ptr->current_buffer_size)
    {
        png_size_t save_size;

        if (png_ptr->idat_size < (png_uint_32)png_ptr->current_buffer_size)
        {
            save_size = (png_size_t)png_ptr->idat_size;

            /* Check for overflow */
            if ((png_uint_32)save_size != png_ptr->idat_size)
                png_error(png_ptr, "save_size overflowed in pngpread");
        }
        else
            save_size = png_ptr->current_buffer_size;

        png_calculate_crc(png_ptr, png_ptr->current_buffer_ptr, save_size);
        if (!(png_ptr->flags & PNG_FLAG_ZLIB_FINISHED))
            png_process_IDAT_data(png_ptr, png_ptr->current_buffer_ptr, save_size);

        png_ptr->idat_size -= save_size;
        png_ptr->buffer_size -= save_size;
        png_ptr->current_buffer_size -= save_size;
        png_ptr->current_buffer_ptr += save_size;
    }
    if (!png_ptr->idat_size)
    {
        if (png_ptr->buffer_size < 4)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_crc_finish(png_ptr, 0);
        png_ptr->mode &= ~PNG_HAVE_CHUNK_HEADER;
        png_ptr->mode |= PNG_AFTER_IDAT;
    }
}

void /* PRIVATE */
png_process_IDAT_data(png_structp png_ptr, png_bytep buffer,
                      png_size_t buffer_length)
{
    int ret;

    if ((png_ptr->flags & PNG_FLAG_ZLIB_FINISHED) && buffer_length)
        png_benign_error(png_ptr, "Extra compression data");

    png_ptr->zstream.next_in = buffer;
    png_ptr->zstream.avail_in = (uInt)buffer_length;
    for (;;)
    {
        ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
        if (ret != Z_OK)
        {
            if (ret == Z_STREAM_END)
            {
                if (png_ptr->zstream.avail_in)
                    png_benign_error(png_ptr, "Extra compressed data");

                if (!(png_ptr->zstream.avail_out))
                {
                    png_push_process_row(png_ptr);
                }

                png_ptr->mode |= PNG_AFTER_IDAT;
                png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
                break;
            }
            else if (ret == Z_BUF_ERROR)
                break;

            else
                png_error(png_ptr, "Decompression Error");
        }
        if (!(png_ptr->zstream.avail_out))
        {
            if ((
                    #ifdef PNG_READ_INTERLACING_SUPPORTED
                    png_ptr->interlaced && png_ptr->pass > 6) ||
                (!png_ptr->interlaced &&
                    #endif
                    png_ptr->row_number == png_ptr->num_rows))
            {
                if (png_ptr->zstream.avail_in)
                    png_warning(png_ptr, "Too much data in IDAT chunks");
                png_ptr->flags |= PNG_FLAG_ZLIB_FINISHED;
                break;
            }
            png_push_process_row(png_ptr);
            png_ptr->zstream.avail_out =
                (uInt)PNG_ROWBYTES(png_ptr->pixel_depth,
                                   png_ptr->iwidth) + 1;
            png_ptr->zstream.next_out = png_ptr->row_buf;
        }

        else
            break;
    }
}

void /* PRIVATE */
png_push_process_row(png_structp png_ptr)
{
    png_ptr->row_info.color_type = png_ptr->color_type;
    png_ptr->row_info.width = png_ptr->iwidth;
    png_ptr->row_info.channels = png_ptr->channels;
    png_ptr->row_info.bit_depth = png_ptr->bit_depth;
    png_ptr->row_info.pixel_depth = png_ptr->pixel_depth;

    png_ptr->row_info.rowbytes = PNG_ROWBYTES(png_ptr->row_info.pixel_depth,
                                              png_ptr->row_info.width);

    png_read_filter_row(png_ptr, &(png_ptr->row_info),
                        png_ptr->row_buf + 1, png_ptr->prev_row + 1,
                        (int)(png_ptr->row_buf[0]));

    png_memcpy(png_ptr->prev_row, png_ptr->row_buf, png_ptr->rowbytes + 1);

    if (png_ptr->transformations || (png_ptr->flags & PNG_FLAG_STRIP_ALPHA))
        png_do_read_transformations(png_ptr);

    #ifdef PNG_READ_INTERLACING_SUPPORTED
    /* Blow up interlaced rows to full size */
    if (png_ptr->interlaced && (png_ptr->transformations & PNG_INTERLACE))
    {
        if (png_ptr->pass < 6)
            /*       old interface (pre-1.0.9):
                     png_do_read_interlace(&(png_ptr->row_info),
                        png_ptr->row_buf + 1, png_ptr->pass, png_ptr->transformations);
             */
            png_do_read_interlace(png_ptr);

        switch (png_ptr->pass)
        {
            case 0:
            {
                int i;
                for (i = 0; i < 8 && png_ptr->pass == 0; i++)
                {
                    png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                    png_read_push_finish_row(png_ptr); /* Updates png_ptr->pass */
                }

                if (png_ptr->pass == 2) /* Pass 1 might be empty */
                {
                    for (i = 0; i < 4 && png_ptr->pass == 2; i++)
                    {
                        png_push_have_row(png_ptr, NULL);
                        png_read_push_finish_row(png_ptr);
                    }
                }

                if (png_ptr->pass == 4 && png_ptr->height <= 4)
                {
                    for (i = 0; i < 2 && png_ptr->pass == 4; i++)
                    {
                        png_push_have_row(png_ptr, NULL);
                        png_read_push_finish_row(png_ptr);
                    }
                }

                if (png_ptr->pass == 6 && png_ptr->height <= 4)
                {
                    png_push_have_row(png_ptr, NULL);
                    png_read_push_finish_row(png_ptr);
                }

                break;
            }

            case 1:
            {
                int i;
                for (i = 0; i < 8 && png_ptr->pass == 1; i++)
                {
                    png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                    png_read_push_finish_row(png_ptr);
                }

                if (png_ptr->pass == 2) /* Skip top 4 generated rows */
                {
                    for (i = 0; i < 4 && png_ptr->pass == 2; i++)
                    {
                        png_push_have_row(png_ptr, NULL);
                        png_read_push_finish_row(png_ptr);
                    }
                }

                break;
            }

            case 2:
            {
                int i;

                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
                {
                    png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                    png_read_push_finish_row(png_ptr);
                }

                for (i = 0; i < 4 && png_ptr->pass == 2; i++)
                {
                    png_push_have_row(png_ptr, NULL);
                    png_read_push_finish_row(png_ptr);
                }

                if (png_ptr->pass == 4) /* Pass 3 might be empty */
                {
                    for (i = 0; i < 2 && png_ptr->pass == 4; i++)
                    {
                        png_push_have_row(png_ptr, NULL);
                        png_read_push_finish_row(png_ptr);
                    }
                }

                break;
            }

            case 3:
            {
                int i;

                for (i = 0; i < 4 && png_ptr->pass == 3; i++)
                {
                    png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                    png_read_push_finish_row(png_ptr);
                }

                if (png_ptr->pass == 4) /* Skip top two generated rows */
                {
                    for (i = 0; i < 2 && png_ptr->pass == 4; i++)
                    {
                        png_push_have_row(png_ptr, NULL);
                        png_read_push_finish_row(png_ptr);
                    }
                }

                break;
            }

            case 4:
            {
                int i;

                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
                {
                    png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                    png_read_push_finish_row(png_ptr);
                }

                for (i = 0; i < 2 && png_ptr->pass == 4; i++)
                {
                    png_push_have_row(png_ptr, NULL);
                    png_read_push_finish_row(png_ptr);
                }

                if (png_ptr->pass == 6) /* Pass 5 might be empty */
                {
                    png_push_have_row(png_ptr, NULL);
                    png_read_push_finish_row(png_ptr);
                }

                break;
            }

            case 5:
            {
                int i;

                for (i = 0; i < 2 && png_ptr->pass == 5; i++)
                {
                    png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                    png_read_push_finish_row(png_ptr);
                }

                if (png_ptr->pass == 6) /* Skip top generated row */
                {
                    png_push_have_row(png_ptr, NULL);
                    png_read_push_finish_row(png_ptr);
                }

                break;
            }
            case 6:
            {
                png_push_have_row(png_ptr, png_ptr->row_buf + 1);
                png_read_push_finish_row(png_ptr);

                if (png_ptr->pass != 6)
                    break;

                png_push_have_row(png_ptr, NULL);
                png_read_push_finish_row(png_ptr);
            }
        }
    }
    else
    #endif
    {
        png_push_have_row(png_ptr, png_ptr->row_buf + 1);
        png_read_push_finish_row(png_ptr);
    }
}

void /* PRIVATE */
png_read_push_finish_row(png_structp png_ptr)
{
    /* Arrays to facilitate easy interlacing - use pass (0 - 6) as index */

    /* Start of interlace block */
    PNG_CONST int FARDATA png_pass_start[] = { 0, 4, 0, 2, 0, 1, 0 };

    /* Offset to next interlace block */
    PNG_CONST int FARDATA png_pass_inc[] = { 8, 8, 4, 4, 2, 2, 1 };

    /* Start of interlace block in the y direction */
    PNG_CONST int FARDATA png_pass_ystart[] = { 0, 0, 4, 0, 2, 0, 1 };

    /* Offset to next interlace block in the y direction */
    PNG_CONST int FARDATA png_pass_yinc[] = { 8, 8, 8, 4, 4, 2, 2 };

    /* Height of interlace block.  This is not currently used - if you need
     * it, uncomment it here and in png.h
       PNG_CONST int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
     */

    png_ptr->row_number++;
    if (png_ptr->row_number < png_ptr->num_rows)
        return;

    #ifdef PNG_READ_INTERLACING_SUPPORTED
    if (png_ptr->interlaced)
    {
        png_ptr->row_number = 0;
        png_memset(png_ptr->prev_row, 0,
                   png_ptr->rowbytes + 1);
        do
        {
            png_ptr->pass++;
            if ((png_ptr->pass == 1 && png_ptr->width < 5) ||
                (png_ptr->pass == 3 && png_ptr->width < 3) ||
                (png_ptr->pass == 5 && png_ptr->width < 2))
                png_ptr->pass++;

            if (png_ptr->pass > 7)
                png_ptr->pass--;

            if (png_ptr->pass >= 7)
                break;

            png_ptr->iwidth = (png_ptr->width +
                               png_pass_inc[png_ptr->pass] - 1 -
                               png_pass_start[png_ptr->pass]) /
                              png_pass_inc[png_ptr->pass];

            if (png_ptr->transformations & PNG_INTERLACE)
                break;

            png_ptr->num_rows = (png_ptr->height +
                                 png_pass_yinc[png_ptr->pass] - 1 -
                                 png_pass_ystart[png_ptr->pass]) /
                                png_pass_yinc[png_ptr->pass];

        }
        while (png_ptr->iwidth == 0 || png_ptr->num_rows == 0);
    }
    #endif /* PNG_READ_INTERLACING_SUPPORTED */
}

    #ifdef PNG_READ_tEXt_SUPPORTED
void /* PRIVATE */
png_push_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
                     length)
{
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
    {
        png_error(png_ptr, "Out of place tEXt");
        info_ptr = info_ptr;  /* To quiet some compiler warnings */
    }

    #ifdef PNG_MAX_MALLOC_64K
    png_ptr->skip_length = 0; /* This may not be necessary */

    if (length > (png_uint_32)65535L) /* Can't hold entire string in memory */
    {
        png_warning(png_ptr, "tEXt chunk too large to fit in memory");
        png_ptr->skip_length = length - (png_uint_32)65535L;
        length = (png_uint_32)65535L;
    }
    #endif

    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
                                                  (png_size_t)(length + 1));
    png_ptr->current_text[length] = '\0';
    png_ptr->current_text_ptr = png_ptr->current_text;
    png_ptr->current_text_size = (png_size_t)length;
    png_ptr->current_text_left = (png_size_t)length;
    png_ptr->process_mode = PNG_READ_tEXt_MODE;
}

void /* PRIVATE */
png_push_read_tEXt(png_structp png_ptr, png_infop info_ptr)
{
    if (png_ptr->buffer_size && png_ptr->current_text_left)
    {
        png_size_t text_size;

        if (png_ptr->buffer_size < png_ptr->current_text_left)
            text_size = png_ptr->buffer_size;

        else
            text_size = png_ptr->current_text_left;

        png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
        png_ptr->current_text_left -= text_size;
        png_ptr->current_text_ptr += text_size;
    }
    if (!(png_ptr->current_text_left))
    {
        png_textp text_ptr;
        png_charp text;
        png_charp key;
        int ret;

        if (png_ptr->buffer_size < 4)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_push_crc_finish(png_ptr);

        #ifdef PNG_MAX_MALLOC_64K
        if (png_ptr->skip_length)
            return;
        #endif

        key = png_ptr->current_text;

        for (text = key; *text; text++)
            /* Empty loop */;

        if (text < key + png_ptr->current_text_size)
            text++;

        text_ptr = (png_textp)png_malloc(png_ptr,
                                         png_sizeof(png_text));
        text_ptr->compression = PNG_TEXT_COMPRESSION_NONE;
        text_ptr->key = key;
        #ifdef PNG_iTXt_SUPPORTED
        text_ptr->lang = NULL;
        text_ptr->lang_key = NULL;
        #endif
        text_ptr->text = text;

        ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);

        png_free(png_ptr, key);
        png_free(png_ptr, text_ptr);
        png_ptr->current_text = NULL;

        if (ret)
            png_warning(png_ptr, "Insufficient memory to store text chunk");
    }
}
    #endif

    #ifdef PNG_READ_zTXt_SUPPORTED
void /* PRIVATE */
png_push_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
                     length)
{
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
    {
        png_error(png_ptr, "Out of place zTXt");
        info_ptr = info_ptr;  /* To quiet some compiler warnings */
    }

    #ifdef PNG_MAX_MALLOC_64K
    /* We can't handle zTXt chunks > 64K, since we don't have enough space
     * to be able to store the uncompressed data.  Actually, the threshold
     * is probably around 32K, but it isn't as definite as 64K is.
     */
    if (length > (png_uint_32)65535L)
    {
        png_warning(png_ptr, "zTXt chunk too large to fit in memory");
        png_push_crc_skip(png_ptr, length);
        return;
    }
    #endif

    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
                                                  (png_size_t)(length + 1));
    png_ptr->current_text[length] = '\0';
    png_ptr->current_text_ptr = png_ptr->current_text;
    png_ptr->current_text_size = (png_size_t)length;
    png_ptr->current_text_left = (png_size_t)length;
    png_ptr->process_mode = PNG_READ_zTXt_MODE;
}

void /* PRIVATE */
png_push_read_zTXt(png_structp png_ptr, png_infop info_ptr)
{
    if (png_ptr->buffer_size && png_ptr->current_text_left)
    {
        png_size_t text_size;

        if (png_ptr->buffer_size < (png_uint_32)png_ptr->current_text_left)
            text_size = png_ptr->buffer_size;

        else
            text_size = png_ptr->current_text_left;

        png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
        png_ptr->current_text_left -= text_size;
        png_ptr->current_text_ptr += text_size;
    }
    if (!(png_ptr->current_text_left))
    {
        png_textp text_ptr;
        png_charp text;
        png_charp key;
        int ret;
        png_size_t text_size, key_size;

        if (png_ptr->buffer_size < 4)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_push_crc_finish(png_ptr);

        key = png_ptr->current_text;

        for (text = key; *text; text++)
            /* Empty loop */;

        /* zTXt can't have zero text */
        if (text >= key + png_ptr->current_text_size)
        {
            png_ptr->current_text = NULL;
            png_free(png_ptr, key);
            return;
        }

        text++;

        if (*text != PNG_TEXT_COMPRESSION_zTXt) /* Check compression byte */
        {
            png_ptr->current_text = NULL;
            png_free(png_ptr, key);
            return;
        }

        text++;

        png_ptr->zstream.next_in = (png_bytep)text;
        png_ptr->zstream.avail_in = (uInt)(png_ptr->current_text_size -
                                           (text - key));
        png_ptr->zstream.next_out = png_ptr->zbuf;
        png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;

        key_size = text - key;
        text_size = 0;
        text = NULL;
        ret = Z_STREAM_END;

        while (png_ptr->zstream.avail_in)
        {
            ret = inflate(&png_ptr->zstream, Z_PARTIAL_FLUSH);
            if (ret != Z_OK && ret != Z_STREAM_END)
            {
                inflateReset(&png_ptr->zstream);
                png_ptr->zstream.avail_in = 0;
                png_ptr->current_text = NULL;
                png_free(png_ptr, key);
                png_free(png_ptr, text);
                return;
            }
            if (!(png_ptr->zstream.avail_out) || ret == Z_STREAM_END)
            {
                if (text == NULL)
                {
                    text = (png_charp)png_malloc(png_ptr,
                                                 (png_ptr->zbuf_size
                                                  - png_ptr->zstream.avail_out + key_size + 1));

                    png_memcpy(text + key_size, png_ptr->zbuf,
                               png_ptr->zbuf_size - png_ptr->zstream.avail_out);

                    png_memcpy(text, key, key_size);

                    text_size = key_size + png_ptr->zbuf_size -
                                png_ptr->zstream.avail_out;

                    *(text + text_size) = '\0';
                }
                else
                {
                    png_charp tmp;

                    tmp = text;
                    text = (png_charp)png_malloc(png_ptr, text_size +
                                                 (png_ptr->zbuf_size
                                                  - png_ptr->zstream.avail_out + 1));

                    png_memcpy(text, tmp, text_size);
                    png_free(png_ptr, tmp);

                    png_memcpy(text + text_size, png_ptr->zbuf,
                               png_ptr->zbuf_size - png_ptr->zstream.avail_out);

                    text_size += png_ptr->zbuf_size - png_ptr->zstream.avail_out;
                    *(text + text_size) = '\0';
                }
                if (ret != Z_STREAM_END)
                {
                    png_ptr->zstream.next_out = png_ptr->zbuf;
                    png_ptr->zstream.avail_out = (uInt)png_ptr->zbuf_size;
                }
            }
            else
            {
                break;
            }

            if (ret == Z_STREAM_END)
                break;
        }

        inflateReset(&png_ptr->zstream);
        png_ptr->zstream.avail_in = 0;

        if (ret != Z_STREAM_END)
        {
            png_ptr->current_text = NULL;
            png_free(png_ptr, key);
            png_free(png_ptr, text);
            return;
        }

        png_ptr->current_text = NULL;
        png_free(png_ptr, key);
        key = text;
        text += key_size;

        text_ptr = (png_textp)png_malloc(png_ptr,
                                         png_sizeof(png_text));
        text_ptr->compression = PNG_TEXT_COMPRESSION_zTXt;
        text_ptr->key = key;
        #ifdef PNG_iTXt_SUPPORTED
        text_ptr->lang = NULL;
        text_ptr->lang_key = NULL;
        #endif
        text_ptr->text = text;

        ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);

        png_free(png_ptr, key);
        png_free(png_ptr, text_ptr);

        if (ret)
            png_warning(png_ptr, "Insufficient memory to store text chunk");
    }
}
    #endif

    #ifdef PNG_READ_iTXt_SUPPORTED
void /* PRIVATE */
png_push_handle_iTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32
                     length)
{
    if (!(png_ptr->mode & PNG_HAVE_IHDR) || (png_ptr->mode & PNG_HAVE_IEND))
    {
        png_error(png_ptr, "Out of place iTXt");
        info_ptr = info_ptr;  /* To quiet some compiler warnings */
    }

    #ifdef PNG_MAX_MALLOC_64K
    png_ptr->skip_length = 0; /* This may not be necessary */

    if (length > (png_uint_32)65535L) /* Can't hold entire string in memory */
    {
        png_warning(png_ptr, "iTXt chunk too large to fit in memory");
        png_ptr->skip_length = length - (png_uint_32)65535L;
        length = (png_uint_32)65535L;
    }
    #endif

    png_ptr->current_text = (png_charp)png_malloc(png_ptr,
                                                  (png_size_t)(length + 1));
    png_ptr->current_text[length] = '\0';
    png_ptr->current_text_ptr = png_ptr->current_text;
    png_ptr->current_text_size = (png_size_t)length;
    png_ptr->current_text_left = (png_size_t)length;
    png_ptr->process_mode = PNG_READ_iTXt_MODE;
}

void /* PRIVATE */
png_push_read_iTXt(png_structp png_ptr, png_infop info_ptr)
{

    if (png_ptr->buffer_size && png_ptr->current_text_left)
    {
        png_size_t text_size;

        if (png_ptr->buffer_size < png_ptr->current_text_left)
            text_size = png_ptr->buffer_size;

        else
            text_size = png_ptr->current_text_left;

        png_crc_read(png_ptr, (png_bytep)png_ptr->current_text_ptr, text_size);
        png_ptr->current_text_left -= text_size;
        png_ptr->current_text_ptr += text_size;
    }
    if (!(png_ptr->current_text_left))
    {
        png_textp text_ptr;
        png_charp key;
        int comp_flag;
        png_charp lang;
        png_charp lang_key;
        png_charp text;
        int ret;

        if (png_ptr->buffer_size < 4)
        {
            png_push_save_buffer(png_ptr);
            return;
        }

        png_push_crc_finish(png_ptr);

        #ifdef PNG_MAX_MALLOC_64K
        if (png_ptr->skip_length)
            return;
        #endif

        key = png_ptr->current_text;

        for (lang = key; *lang; lang++)
            /* Empty loop */;

        if (lang < key + png_ptr->current_text_size - 3)
            lang++;

        comp_flag = *lang++;
        lang++;   /* Skip comp_type, always zero */

        for (lang_key = lang; *lang_key; lang_key++)
            /* Empty loop */;

        lang_key++;      /* Skip NUL separator */

        text = lang_key;

        if (lang_key < key + png_ptr->current_text_size - 1)
        {
            for (; *text; text++)
                /* Empty loop */;
        }

        if (text < key + png_ptr->current_text_size)
            text++;

        text_ptr = (png_textp)png_malloc(png_ptr,
                                         png_sizeof(png_text));

        text_ptr->compression = comp_flag + 2;
        text_ptr->key = key;
        text_ptr->lang = lang;
        text_ptr->lang_key = lang_key;
        text_ptr->text = text;
        text_ptr->text_length = 0;
        text_ptr->itxt_length = png_strlen(text);

        ret = png_set_text_2(png_ptr, info_ptr, text_ptr, 1);

        png_ptr->current_text = NULL;

        png_free(png_ptr, text_ptr);
        if (ret)
            png_warning(png_ptr, "Insufficient memory to store iTXt chunk");
    }
}
    #endif

/* This function is called when we haven't found a handler for this
 * chunk.  If there isn't a problem with the chunk itself (ie a bad chunk
 * name or a critical chunk), the chunk is (currently) silently ignored.
 */
void /* PRIVATE */
png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32
                        length)
{
    png_uint_32 skip = 0;

    if (!(png_ptr->chunk_name[0] & 0x20))
    {
        #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
        if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
            PNG_HANDLE_CHUNK_ALWAYS
            #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
            && png_ptr->read_user_chunk_fn == NULL
            #endif
            )
        #endif
        png_chunk_error(png_ptr, "unknown critical chunk");

        info_ptr = info_ptr; /* To quiet some compiler warnings */
    }

    #ifdef PNG_READ_UNKNOWN_CHUNKS_SUPPORTED
    if (png_ptr->flags & PNG_FLAG_KEEP_UNKNOWN_CHUNKS)
    {
        #ifdef PNG_MAX_MALLOC_64K
        if (length > (png_uint_32)65535L)
        {
            png_warning(png_ptr, "unknown chunk too large to fit in memory");
            skip = length - (png_uint_32)65535L;
            length = (png_uint_32)65535L;
        }
        #endif
        png_memcpy((png_charp)png_ptr->unknown_chunk.name,
                   (png_charp)png_ptr->chunk_name,
                   png_sizeof(png_ptr->unknown_chunk.name));
        png_ptr->unknown_chunk.name[png_sizeof(png_ptr->unknown_chunk.name) - 1]
            = '\0';

        png_ptr->unknown_chunk.size = (png_size_t)length;

        if (length == 0)
            png_ptr->unknown_chunk.data = NULL;

        else
        {
            png_ptr->unknown_chunk.data = (png_bytep)png_malloc(png_ptr,
                                                                (png_size_t)length);
            png_crc_read(png_ptr, (png_bytep)png_ptr->unknown_chunk.data, length);
        }

        #ifdef PNG_READ_USER_CHUNKS_SUPPORTED
        if (png_ptr->read_user_chunk_fn != NULL)
        {
            /* Callback to user unknown chunk handler */
            int ret;
            ret = (*(png_ptr->read_user_chunk_fn))
                      (png_ptr, &png_ptr->unknown_chunk);

            if (ret < 0)
                png_chunk_error(png_ptr, "error in user chunk");

            if (ret == 0)
            {
                if (!(png_ptr->chunk_name[0] & 0x20))
                    if (png_handle_as_unknown(png_ptr, png_ptr->chunk_name) !=
                        PNG_HANDLE_CHUNK_ALWAYS)
                        png_chunk_error(png_ptr, "unknown critical chunk");
                png_set_unknown_chunks(png_ptr, info_ptr,
                                       &png_ptr->unknown_chunk, 1);
            }
        }

        else
        #endif
        png_set_unknown_chunks(png_ptr, info_ptr, &png_ptr->unknown_chunk, 1);
        png_free(png_ptr, png_ptr->unknown_chunk.data);
        png_ptr->unknown_chunk.data = NULL;
    }

    else
    #endif
    skip = length;
    png_push_crc_skip(png_ptr, skip);
}

void /* PRIVATE */
png_push_have_info(png_structp png_ptr, png_infop info_ptr)
{
    if (png_ptr->info_fn != NULL)
        (*(png_ptr->info_fn))(png_ptr, info_ptr);
}

void /* PRIVATE */
png_push_have_end(png_structp png_ptr, png_infop info_ptr)
{
    if (png_ptr->end_fn != NULL)
        (*(png_ptr->end_fn))(png_ptr, info_ptr);
}

void /* PRIVATE */
png_push_have_row(png_structp png_ptr, png_bytep row)
{
    if (png_ptr->row_fn != NULL)
        (*(png_ptr->row_fn))(png_ptr, row, png_ptr->row_number,
                             (int)png_ptr->pass);
}

void PNGAPI
png_progressive_combine_row(png_structp png_ptr,
                            png_bytep old_row, png_bytep new_row)
{
    PNG_CONST int FARDATA png_pass_dsp_mask[7] =
    { 0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff };

    if (png_ptr == NULL)
        return;

    if (new_row != NULL)   /* new_row must == png_ptr->row_buf here. */
        png_combine_row(png_ptr, old_row, png_pass_dsp_mask[png_ptr->pass]);
}

void PNGAPI
png_set_progressive_read_fn(png_structp png_ptr, png_voidp progressive_ptr,
                            png_progressive_info_ptr info_fn, png_progressive_row_ptr row_fn,
                            png_progressive_end_ptr end_fn)
{
    if (png_ptr == NULL)
        return;

    png_ptr->info_fn = info_fn;
    png_ptr->row_fn = row_fn;
    png_ptr->end_fn = end_fn;

    png_set_read_fn(png_ptr, progressive_ptr, png_push_fill_buffer);
}

png_voidp PNGAPI
png_get_progressive_ptr(png_structp png_ptr)
{
    if (png_ptr == NULL)
        return (NULL);

    return png_ptr->io_ptr;
}
#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */